1. Field of the Invention
The present invention relates to a process for producing a substrate for a liquid ejection head.
2. Description of the Related Art
An ink jet recording method has such an advantage that only a negligibly small noise is generated during recording, and an advantage that high-speed recording can be performed without subjecting plain paper to special processing.
Further, among ink jet recording heads, an ink jet recording head capable of ejecting ink droplets in a perpendicular direction with respect to a base member on which an ejection energy generating element is formed is referred to as “side-shooter type recording head”. In such a side-shooter type recording head, ink supply to an ink flow path is performed via a through-hole provided in the base member (also called “element substrate”) on which a thermoelectric conversion element corresponding to the ejection energy generating element is formed.
As measures of forming an ink supply port in the element substrate of the ink jet recording head of this type, there have been proposed a method using a drill or a laser, and methods such as sandblasting and crystal anisotropic etching.
In U.S. Pat. No. 7,438,392, there is disclosed a method so-called a Bosch process in which etching of the substrate and coating of an etched side surface are repeated to form the through-hole in the substrate.
Through use of the Bosch process to form the ink supply port, the ink supply port can substantially perpendicularly be formed, and hence the chip size can be smaller than that in the case where the ink supply port is formed by crystal anisotropic etching.
Further, in Japanese Patent Application Laid-Open No. 2009-61663, there is disclosed a method in which an etch stop layer is provided when the ink supply port is formed by the Bosch process.
As in the technologies described in U.S. Pat. No. 7,438,392 and Japanese Patent Application Laid-Open No. 2009-61663, with a substantially-perpendicular ink supply port, the chip size can be reduced.
When the ink supply port is formed with use of the etch stop layer and the Bosch process as described in U.S. Pat. No. 7,438,392 and Japanese Patent Application Laid-Open No. 2009-61663, a step of removing the etch stop layer is necessary after dry etching is completed. Note that, the etch stop layer is generally removed by wet etching after the dry etching is completed.
Further, the Bosch process is performed by repeating a step of etching and a step of deposition, but eventually, a deposited film (hereinafter, also referred to as deposition film) remains on a side wall of the ink supply port. When the ink jet recording head is produced under such a condition that this deposition film is adhered on the side wall, printing performance may be reduced.
The deposition film that has adhered on the side wall of the ink supply port can be removed through immersion in HFE or the like, but similarly to the above-mentioned step of removing the etch stop layer, addition of other steps is required.